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McStas: Bender Component

[ Identification | Description | Input parameters | Output parameters | Links ]

The Bender Component

Models a curved neutron guide.

Identification

  • Author: Philipp Bernhardt
  • Origin: Uni. Erlangen (Germany)
  • Date: Februar 7 1999
  • Version: $Revision$

Description

Models a curved neutron guide with cylindrical walls.

Bender radius, entrance width and height are necessary input data. To define
the bender, you may either enter the deviation angle 'Win' or the length 'l'.
The bender may consist of 'k' vertical channels, separated by partitioning walls
of thickness 'd'. Three different reflectivity profiles can be given: for outer
walls, for inner walls and for the top and bottom walls. The partitioning walls
have the same coating as the exterior walls.

The entrance lies in the X-Y plane, centered on the Z axis. The neutrons will
also leave the bender in the X-Y plane at the z-value l=r*Win, i.e. they are
centred on (0,0,r*Win); they have an (average) flight direction along the z-axis.
Therefore, the following component is adjacent, if positioned AT (0,0,r*Win)
without rotation.
So, seen from outside, it behaves like a straight guide along the Z axis. As a
consequence, it is shown straight in 'mcdisplay'.
This behaviour results from a co-ordinate transformation inside the component.
It is done to facilitate its use. Neither rotation nor shift along the x-axis
need to be calculated; a new arm is not necessary. Internally, the bender is
bent to the negative X axis;

Example:
Bender of 120 mm height, 50 mm width, 250 m radius and 0.04 rad (or 2.292 deg) curvature
not channeled, with a standard m=2 coating on

Bender(w=0.05,h=0.12,r=250,Win=0.04,
       R0a=0.99,Qca=0.021,alphaa=6.07,ma=2,Wa=0.003,
       R0i=0.99,Qci=0.021,alphai=6.07,mi=2,Wi=0.003,
       R0s=0.99,Qcs=0.021,alphas=6.07,ms=2,Ws=0.003)

%BUGS
Some users have reported potentially strange behaviours with this component.
This component does not work with gravitation on.

Input parameters

Parameters in boldface are required; the others are optional.
Name Unit Description Default
w m Width at the bender entry and exit  
h m Height at the bender entry and exit  
r m Radius of the bender  
Win rad Angle of the deflection of the whole bender 0.04
k 1 Number of channels inside the bender 1
d m Thickness of one blade separating the channels 0.001
l m length of bender l=r*Win 0
R0a 1 Low-angle reflectivity at the outer side of the bender 0.99
Qca AA-1 Critical scattering vector 0.021
alphaa AA Slope of reflectivity 6.07
ma 1 m-value of material 2
Wa AA-1 Width of supermirror cut-off 0.003
R0i 1 Low-angle reflectivity at the inner side of the bender 0.99
Qci AA-1 Critical scattering vector 0.021
alphai AA Slope of reflectivity 6.07
mi 1 m-value of material 2
Wi AA-1 Width of supermirror cut-off 0.003
R0s 1 Low-angle reflectivity at the top and bottom side of the bender 0.99
Qcs AA-1 Critical scattering vector 0.021
alphas AA Slope of reflectivity 6.07
ms 1 m-value of material 2
Ws AA-1 Width of supermirror cut-off 0.003

Output parameters

Name Unit Description Default
bk m Width of 1 channel + 1 separating blade  
mWin rad Angle of the deflection of the whole bender  

Links


[ Identification | Description | Input parameters | Output parameters | Links ]

Generated automatically by McDoc, Peter Willendrup <peter.willendrup@risoe.dk> / Fri Mar 17 20:40:06 2017


Last Modified: Friday, 17-Mar-2017 21:40:06 CET
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